Objectives. This study tested a recent theoretical development in stress research to see whether group membership influenced cardiovascular reactions following exposure to acute stress.Methods. Participants (N = 104) were exposed to a message in which a maths test was described as stressful or challenging by an ingroup member (a student) or outgroup member (a stress disorder sufferer). Systolic blood pressure and diastolic blood pressure (DBP) and heart rate (HR) were monitored throughout a standard reactivity study.Results. As expected, a significant interaction was found; relative to those who were told that the task was challenging, ingroup members reported more stress and had higher DBP and HR reactivity when told by an ingroup member that the maths task was stressful; task information did not have the same effect for outgroup members.Conclusion. These results indicate that informational support is not constant but varies as a function of group membership. Finally, this recent development in stress research may prove useful for those interested in investigating the interactions between social, psychological and physiological processes underlying health disparities.